About Chambers USAChambers USA ranks attorneys and law firms based on reputation. Researchers spend six months speaking with clients and lawyers across the United States and conduct thousands of in-depth telephone interviews. Law firms and individual attorneys are then ranked based on the interviews. Ranking criteria includes technical legal ability, professional conduct, client service, commercial awareness and astuteness, diligence, commitment and other qualities most valued by clients. Inclusion in the guide is based solely on the research team’s findings. No one can buy their way in.